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Car has never run better...

I

imported_Ron Vogel

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So, I had some issues at Cordova about a month ago, car was fueling poorly, but still had a PB. On the way home the car sputtered and cut out a few times. The next time I drove to work, and the car died several times. Traced it down to the Maf connector, spliced the wires to band aid it, and fixed it. Picked up some new GM connectors from Justin, but didn't replace. So lately, throttle response hasn't been so hot, last time at the track was down 2 mph, with no KR on a smaller pulley; chalked it up to poor weather.
Fast forward to today...Car started sputtering on the way to work again. I barely got it home, figured my splice gave up, so I started putting on the connector I got from Justin.
Well, I clipped the wires, then stripped back the wires on the harness side..and they were corroded under the sheathing. In fact, I had to cut back the wires 6 inches to find good wire!
I just took it out for a drive, and holy crap! Major throttle response! Engine has never pulled so hard, or idled so smooth. Thought I'd share this just in case the corrosion under the wires is fairly common. Weird thing is, I set a code for TPS, not the maf. After fixing the maf wires, I tapped the car and found no issues what so ever with the TPS, I suspect that the wiring is somehow connected between the TPS and the Maf that if one is bad it affects the other.
 

Fish

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Thats cool that your cars running well. Hope to see a new PB.
 
I

imported_Ron Vogel

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I talked to Justin today about Zacks car. Funny thing was that Justin had someone over at his place yesterday with the same syptoms as Zacks car, and Alex's car for that matter. All cars had LT's pegged at idle, but went to normal during acceleration. From what I saw, Zack's 02 sensor was bad, it just dwelled low at idle and then went to 1.1 volts if you mashed the gas. Justin pulled the maf connection off then the 02 read normal. Weird. IIRC you also had something similar right?
 

gtphale

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Did you happen to notice the code and if your timing locked in at 10 deg advance? Wonder if my wiring went bad now. I spliced mine about three years ago.
 

mybluegtp

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I'm actually running a stock TB now but still having issues when I floor it when I get this stutter and then the car goes, but if I slowly step on it and then floor it then it will run fine.


I dunno! :confused:
 
I

imported_Ron Vogel

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Originally posted by gtphale@Aug 11 2004, 09:24 PM
Did you happen to notice the code and if your timing locked in at 10 deg advance? Wonder if my wiring went bad now. I spliced mine about three years ago.
I got two codes, intermittent TPS voltage, and low tps voltage. Both went away when I fixed the maf wiring.
 

Mike K

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The two sensors might share a common ground.
 

beyerch

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All cars had LT's pegged at idle, but went to normal during acceleration. From what I saw, Zack's 02 sensor was bad, it just dwelled low at idle and then went to 1.1 volts if you mashed the gas. Justin pulled the maf connection off then the 02 read normal
If you disconnect the MAF the car goes into a backup table mode. Fueling is dictated by a static table and the reason the O2's probably cleaned up was because of the fueling dictated in those tables.

Also, TPS, MAF, and O2 I think are on the same circuit so that would explain the issue wtih the TPS error when the maf was bad.
 

beyerch

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Trims pegged Positive at idle are usually a sign of a vacuum leak/Unaccounted air. Extra air is getting into the engine and the O2 sensor is reporting this to the PCM. The PCM modifies the pulsewidth via the trim to increase fuel output. Hence the high Trim.
A second way to verify vacuum leak is to check your IAC count. If its lower than mid 40's at idle, then you have some form of leak. If you have home ported your throttle body, it could be possible that extra air is getting by the Throttle blade or that your MAF sensor is not properly reading the air entering.


If you have negative trims, it could be O2 sensor going bad, bad MAF sensor, or poorly tuned pcm/ICCU/AFC, etc, etc.
 
I

imported_Ron Vogel

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Originally posted by beyerch@Aug 12 2004, 12:37 AM
Trims pegged Positive at idle are usually a sign of a vacuum leak/Unaccounted air. Extra air is getting into the engine and the O2 sensor is reporting this to the PCM. The PCM modifies the pulsewidth via the trim to increase fuel output. Hence the high Trim.
A second way to verify vacuum leak is to check your IAC count. If its lower than mid 40's at idle, then you have some form of leak. If you have home ported your throttle body, it could be possible that extra air is getting by the Throttle blade or that your MAF sensor is not properly reading the air entering.


If you have negative trims, it could be O2 sensor going bad, bad MAF sensor, or poorly tuned pcm/ICCU/AFC, etc, etc.
Charles, this is the weird thing...all three cars have stock TBs, and soon as the throttle is depressed trims go to normal. I went over Zacks motor with propane and couldn't find any leaks, and I'm sure Alex's car has been gone over for the last year it's been having this problem. It's just very strange that there are three cars with different mods that have the exact same problem.
 

alexgtp

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SO i was thinkng about changing out the MAF and also getting a new 02..

But i did as charles suggested..
I checked mY IAC and they were below 40.. and my ltrims were pegged at 16.4 .

But i fixed the issues with the ICCU..

I cant seem to find any dam vacuum leaks.. Im stumped..
 

rob

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Originally posted by beyerch@Aug 12 2004, 12:37 AM
Trims pegged Positive at idle are usually a sign of a vacuum leak/Unaccounted air. Extra air is getting into the engine and the O2 sensor is reporting this to the PCM. The PCM modifies the pulsewidth via the trim to increase fuel output. Hence the high Trim.
A second way to verify vacuum leak is to check your IAC count. If its lower than mid 40's at idle, then you have some form of leak. If you have home ported your throttle body, it could be possible that extra air is getting by the Throttle blade or that your MAF sensor is not properly reading the air entering.


If you have negative trims, it could be O2 sensor going bad, bad MAF sensor, or poorly tuned pcm/ICCU/AFC, etc, etc.
Dont mean to highjack this post but this is why I dont think my idle delemma isnt a vac leak. My LT's look good at idle.
 

rob

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Propane, good idea Ron. I must be stupid not to have thought of that.
 

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